Permanent magnets are only capable of generating magnetic fields of up to approximately 1 Tesla, thereby rendering them inadequate for applications that rely on higher magnetic fields, such as generators, motors, flywheels, magnetic levitation, magnetic resonance imaging (MRI) and research magnets. The generation of magnetic fields above 1 Tesla requires the use of electromagnets, which greatly increases the implementation cost of these technologies.
Since the discovery of iron-based superconductors in 2008, a tremendous amount of research has been focused on the synthesis and study of these superconductors. Much of the research has been driven by reports of properties that are very appealing for applications, including low anisotropy (around 1-2), high upper critical fields (Hc2) (in excess of 90 T) and intrinsic critical current densities (above 1 MAcm−2 (0 T, 4.2 K)). Unfortunately, soon after their discovery the grain boundaries in these iron-based superconductor materials were observed to block current, similar to rare-earth barium cuprate (REBCO) materials such as YBa2Cu3O7-x (YBCO), but to a somewhat lesser extent. Remarkably, fine-grain, randomly oriented K-doped BaFe2As2 (Ba122) has been synthesized with global critical current density around 10 kAcm−2 (4.2 K, 10 T) and textured tapes of K-doped Ba122 and SrFe2As2 (Sr122) have now been produced that raise Jc by another order of magnitude.
While mechanically reinforced superconducting REBCO (Gd—Ba—Cu—O) materials are known in the art that produce record levels of trapped magnetic fields (up to 17.6 Tesla), these magnetically reinforced superconducting materials are limited in size (radius≤50 mm) because grain boundaries in the material block current flow, forcing samples of the material to be grown as single crystals to eliminate the grain boundaries. In contrast the superconductor, MgB2 is not subject to intrinsic current blocking and as such, can be manufactured as large diameter polycrystalline bulks to trap magnetic fields. However, the trapped magnetic field of MgB2 has been shown to be limited to around 3 T, which is inadequate for high magnetic field applications.
Accordingly, what is needed in the art is a superconducting material having geometric versatility and improved magnetic field trapping of high magnetic fields at lower temperatures.